Network devices are designed to interoperate with each other in networks to carry services. Networks are becoming increasingly more complex, both in terms of the diversity of hardware components as well as in the functionality of the operating systems. The increased complexity and sophisticated network management systems must be learned by human operators. From the view of a network operator, the operational expenditure to successfully run a network is increasing.
One source of increased complexity is configuration of the network and devices. When building networking infrastructure, each node is configured to communicate with other nodes and for the nodes to be reachable for operations, administration, and management (OAM) purposes. External attacks and operational mistakes may break OAM, such as a user configuring a router in a way that breaks network connectivity. Service providers may add clamshell security (e.g., harden the connectivity to the outside), but hardening from external attacks still leaves the network open to operational mistakes and is a complex exercise prone to mistakes that may also break necessary OAM connectivity. Internal hardening of the configuration on a network typically involves many different manual settings and processes, possibly resulting in bringing down the network due to operator mishaps. The OAM may be isolated from the normal network operations by a variety of ad-hoc mechanisms (e.g., additional L2-VLAN for OAM, separate virtual routing and forwarding (VRF), or use of a totally separate physical network for OAM purposes only). However, the isolated OAM may be brought down due to user misconfiguration. Transport networks, such as MPLS-TP, often have their own shoed individual OAM-control plane that provides a transport-network specific set of OAM functions, but does not include the whole list of common OAM functions and is not extensible. All of these mechanisms come with a variety of downsides, including requiring user training for configuration knowledge.